Suction roll for paper-making machines



Feb. 18, 1958 H. HOLDEN l 2,823,593

sUcTIoN ROLL FOR PAPER-MAKING MACHINES Filed Feb. 3, 1955 2 Sheets-Sheet l ,f .i '1. l] l [l F/GB22 .27 24 25 '26 2/23 24 22 lnvenfof 77W; w44.; Wauw/ v Attorneys Feb. 18, 1958 H. HOLDEN 2,823,593

sUcTIoN ROLL FOR PAPERMAKING MACHINES Filed Feb. s., 1955 2 sheets-sheet 2 lil I.

/2 n ven tor A ltorneys United States Patent() SUCTION ROLL FOR PAPER-MAKING'MACHINES Herbert Holden, Shetlield, England, assignor to Beloit iron Worlrs, Beloit, Wis., a corporation of Wisconsin Application February 3, 1955, Serial No. 486,608

Claims priority, application Great Britain February 22, 1954 11 Claims. (Cl. 92--53) This invention relates to the suction rolls of paper-making machines, i. e., rolls having a perforated shell'rotatable about an internal suction box with arcuate sealing strips towards the ends of the shell and longitudinal sealing strips to deiine the arcuate width to which suction is applied from the mouth of the box through the perforations of the shell to a paper web directed over the outside of the shell. The suction box is supported at its ends beyond the ends of the shell, usually with adjustable cornpression springs urging it in a direction to eiect contact between the sealing strips and the shell, the initial degree or" contact being governed by adjustable limit stops in opposition to the springs. When suction is applied it operates to draw the box and the arcuate portion of the shell embraced by the mouth of the box between the longitudinal strips towards each other, thus adding to eachy strip a load amounting to approximately one-half of the product of the projected embraced area of the shell and the amount of negative pressure per unit of area corresponding to the applied suction. Thegreater the embraced arc, the greater the load on each strip per unit of length of the box; and the greater the roll-length the greater the load.'

The suction being uniformly distributed, and the suction box being eased from the shell by the limiting stopsY at the end of the box, the suction box operates as a beam subjected to a uniformly distributed` load and when in operation tends to deflect towards the portion of the shell embraced between its longitudinal sealing strips (or deckles). As a result, greater load is applied tothe centre of each strip than lto its ends. Although it is known to provide for radial movement of ythe strips with respect to the edges of the box and to urge the strips outwardly by springs into floating engagement with the shell, such a construction is complicated4 and adds substantially to the already considerable weight of the box.

It is therefore advantageous to have the strips litting thel full depth of radial slots in the edges of the box. However, this means that the strips must follow the dellection of the box, and the greater load towards the centre results in wearing of the strip to a greater degree at the centre than at the ends. When suction is removed from the box, the absence of deecting force arising from suction leaves the centre of the strip outofcontact with the shell, so that on refapplication of suction there is a gap along the strip through which the suction can draw air, and.` in somey According to the present invention, a beam-likesuction box for a suction roll of a paper-making machine. with further compartment.

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iixed longitudinal Asealing strips 'along the edges of the suction compartment of the box to contact the roll shell is provided with a longitudinal beam secured at its ends Yonly to the suction box and with a further longitudinal suction compartment in communication with the main 'suction compartment, one boundary surface of this further compartment nearer the sealing edges at the mouth of the main compartment being constituted by a wall of the suction box itself and the other boundary surface farther from the sealing edges of the main compartment being connected to the longitudinal beam over the length of'tha't beam.

The beam support may, however, be external Vto the suction box, and is then preferably duplicated, twoilanged beams lying alongside the sides of the box. Thus the ends of one flange of each beam may be secured externally to a body portion of the box of hollow generally rectangular section, and the depth of the beams may be such that the other flange of each extends beyond the outer wall of the hollow section, to be connected along their length' to the boundary surface of the further suction compartment, which surface extends between the beams. y

With that boundary surface in the form of a plate kwith a llexible seal round its entire periphery and the outer wall of the hollow section, that outer wall completes the In this case also, the communication between the compartment may consist of a tube passing uninterruptedly through the hollow section. g

The principle of the invention, and two embodiments of that principle, will now be described in greater detail with reference to the accompanying drawings, in which;v

Figures l to 8 are diagrammatical illustrations co`m= paring the results obtained in practice using a suction box according to the invention (Figures 5 to 8) with the results obtained using a suction box of conventional design (Figures l to 4);

Figure 9 is a fragmentary vertical section on the axis of one form of suction box according to the invention and showing the method of supporting the suction boxwithin a suction roll;

Figure l() isa section on the line 1010 of Figure 9;v

Figure 11 is a side elevation of another form of suc; tion box according to the invention; and

Figure 12 is a vertical section on the line 121-12Y of Figure 1l.

Figure 1 shows a transverse section throughl aI suction box 10 of conventional design having arcuate sealing strips (or deckles) 11 towards its ends and longitudinal sealing strips 12 to define the arcuate Width to which suction is applied from the mouth of the box 'through the perforations of a roll shell 13 t'o a paper web (not shown) directed over the outside of the shell. The body of the box 10 is of rectangular section 14, suction being applied to the defined arc from a chamber 15l havinga connection 16 (Figure 2) to a vacuum pump (not shown). The suction box it) is supported at its ends beyond the ends of the shell i3, with adjustable compression springs urging it in a direction to eifectcontact between the,v sealing strips 11, 12 and the shell, the initial degreey of contact being governed by adjustable limit stops inopposition to the springs, e. g. in the manner shownin Figv ure 9. In Figures 2 to 4 and 6 to 8, the spring react-ions on the roll are indicated at R and the stop reactions arev 2. With no suction applied and the initial degree of contact between the sealing strips and shell set at the tributed over the length between the arcuate sealingl strips 11, the suction box operates as a beam subjected to a uniformly distributed load with reactions P at its ends (Figure 3) and detiects towards the shell 13 by an amount a roughly midway between the arcuate strips 11. As a result, greater load is applied to the centre of each strip than to its ends. The wear at the centre of the strips is consequently greater, and the power required to drive the roll greatly increased. Further, when the application of suction to the chamber 15 is stopped, and the box 10 again deflects under its own weight, whilst supported solely by the spring reactions R (Figure 4), owing to the wear being greater at the centre of the sealing strips than at the ends, the absence of deflecting force arising from suction leaves the centres of the strips 12 out of contact with the shell 13 by an amount b, so that on re-application of suction there is a gap along the strips through which the suction can draw air into the chamber 15, and in some cases the gap may be so large that the suction cannot pull the box 16 back into sealing contact with the shell 13. The wider or longer the mouth of the box, the greater the suction loading producing box deflection and strip wear and the greater the resultant gap. p

Figures to 8, corresponding to Figures 1 to 4, show diagrammatically a suction box according to the invention. The suction box 17 with fixed longitudinal sealing strips 18 and arcuate sealing strips 19 towards the ends of the box forming a suction compartment 20, is provided with a longitudinal beam 21 secured at its ends only (represented diagrammatically at 22) to the suction box and with a further longitudinal suction compartment 23 communicating through tubes 24 with the main suction compartment 20, with the boundary surface of the compartment 23 nearer the sealing edges of the compartment 20 being the lower wall 25 of the rectangularfsection 26 of the box 17 itself and the other boundary surface farther from the sealing edges of the compartment 20 being a plate 27 connected to the beam 21 over the length of that beam. The compartment 23 is sealed by flexible strips 30 secured to the plate 27 and the body of the box 17. The suction box 17 has a connection 28 to a vacuum pump (not shown) by which suction may be applied through the compartment 2i) and the perforations of a roll shell 29 to a paper web (not shown) directed over the outside of the shell.

As with the conventional design of suction box, the suction box 17 is installed with the edges carrying the sealing strips 18 formed to be parallel to the axis of the roll shell 29 when the box supported at its two ends deects downwardly under its own weight with no suction applied (Figure 6). When suction is applied, the suction in the further compartment 23 acting on the beam 21 opposes the upward deection of the box 17 arising from the suction and reduces the central lift of the box to an amount c (Figure 7). Wear of the centre of the strips 18 in operation is correspondingly reduced, so that when the suction is removed, the gap formed at the centre of the strips as the box 17 again deects downwardly is narrowed down to an amount d (Figure 8). By suitable proportioning of the whole box assembly, this gap may in some cases be kept so narrow that it quickly becomes sealed by water on starting the roll in operation, so that the applied suction is soon effective to pull the box into full sealing contact with the shell.

Although the rolls are shown in Figures l to 8 as having shells of plain perforated metal, e. g., bronze, such i 4 rolls being used for suction couches of paper machines and suction drum presses of paper-board machines, the invention may be applied to suction boxes for use with rubber-covered rolls as shown in Figures 9 to l2, such rubber-covered rolls being very frequently used in the press-sections of Fourdrinier machines.

The effective area of the further suction compartment is not necessarily equal to the projected area of the main compartment. For instance, in the case where the mouth of the main compartment is substantially wider than the body of the box (as in the accompanying figures), it may not be convenient to provide a further compartment materially different in width from the box; but the opposing deecting force provided by the further compartment still cancels a substantial proportion of the main deflecting force.

Because of the reduction in the pressure between thc sealing strips and the roll shell effected by the reduced deflection of the box under suction, substantially less power is required to drive the roll.

There may be more than one main suction compartment lengthwise of the mouth side of the box, to operate under different degrees of vacuum, e. g. by connecting each separately to its own source of vacuum. In such case, the compartment producing the larger deecting tendency on the box should be the one connected to the further suction compartment.

Apart from the advantages of the reduced deilection in operation by way of (a) the reduced wear at the centre of the sealing strips leaving narrower centre gaps when the suction is removed, and consequent ease of pulling the box back into position when the suction is reapplied, and (b) the reduction in driving power because of the reduced load on the sealing strips, the main box is subjected to less stress and may itself be made of lighter section.

Moreover, since the further compartment is subjected to suction by its connection with the main compartment and does not add vto the vacuum requirements once the roll is in operation, no additional vacuum pump isrequired beyond the one serving the main compartment.

The invention may be readily applied to suction boxes of generally usual design as shown in Figures 9 and 10, in which a suction box 31 has a body 32 of hollow rectangular section and two suction compartments 33, 34 which apply suction through the perforations of a roll shell 35 having a rubber covering 36 to a paper web (not shown) directed over the outside of the roll 35, the area to which suction is applied being defined by mixed longitudinal sealing strips 37 and adjustable arcuate sealing strips (or deckles) 38, 39. A longitudinal beam 40 of I-section is located inside the body section 32 with the ends only of one flange 40A bolted to pads 41 on the inner wall 42 adjacent to the main (or large) compartment 33. The opposite (outer) wall 43 is removable for insertion of the beam within the section. The point of attachment 44 of the end of the beam 40 is shown falling short of the end of the section 32 to allow for the end of the main compartment 33 to splay at 44 into line with a suction connection 45. Beyond this point, the beam is similarly splayed at 46 to provide its other ilange 40B with a length more nearly equal to the length of the main compartment 33.

The other ange of the beam 40 lies clear of the removable wall 43 and is connected by studs 47 along its length passing through holes 48 in the wall 43 to a plate 44 spaced beyond the wall 43 and exibly sealed at 50 round its entire periphery to the wall. The holes 48 are sealed by bellows 51. The space between the plate 49 and the wall 43 forms a further suction compartment 52 to be maintained under suction by pipe connections 53 (only one shown) traversing the box section from the main suction compartment 33.

The roll shell 35 has a hollow journal 54 with a bearing surface 5 5 resting in a half-bearing 56 and the roll is driven by means of a gear S7. 'I'he suction connection 45 is rigidly attached to the body of the suction box 31 and supports the box through a screw adjustable spring 58 between the facings 59 of a guide 60 which is supported in a bracket 61 from the machine framing (not shown) and having a cap 62, whereby the guide may be readily removed to allow the suction box 31 to be with-y drawn from the roll 35. The spring 58 lurges the suction box 31 towards the shell 35 and the initial degree of contact between the sealing strips 37, 38, 39 is controlled by two adjusting screws 63 contacting the suction connection on either side of a control rod 64 which has a screwed portion 65 for lengthwise adjustment of the arcuate sealing strip 3S. The other end of the suction box is similarly supported, but since there is no suction connection at the other end (not shown) a solid or closed up hollow member of similar exterior shape and size to the suction connection is rigidly attached to the end of the suction box body.

Under suction in the main compartment 33, the centre of the box section tries to delect towards the mouth of the box and the plate 49 forming the far boundary wall of the further compartment 52 deects in the same direction. But the centre of the bottom 43 of the box section forming the other boundary wall is urged in the opposite direction. The plate 49 being connected by the studs 47 to the free ange of the beam 40, the centre of the beam is caused to deflect towards the mouth o-f .the box, but this deection is not communicated to the box section, because the beam is only secured at its ends 41 to the box section. The beam thus provides a resistance to the delection of the box section towards the mouth of the box as the net result of the application of suction to the further compartment 52. In other words, the distributed load resulting from suction is reduced, and the amount by which it is reduced is applied in equal parts at each end of the box, where it does not produce any material decction of the box.

In Figures 1l and l2, a suction box 66 has two channels 67 externally along its sides, the channels 67 being secured to pads 68 on the section only at the ends of one ange 67A of each. The other flange 67B of each channel 67 extends beyond the integral wall 69 of the box section and a plate 70 across these flanges 67B is secured to them over its whole length by bolts 71. The plate is flexibly sealed at 72 to the wall 69 of the box, from which it is spaced to form a further suction compartment 73. Pipe connections 74 across the box communicate with the main suction compartment 75. The plate 70 is transversely stilened by T-angles 76, but it deflects over its length under the applied suction to an. amount determined by the two channels 67 to which 1t 1s secured. This construction may be applied with but little modilication of existing suction box designs.

What I claim is:

1. In a suction box structure for suction roll of a paper makmg machine, xed longitudinal sealing strips adapted to contact the roll shell to define edges of a main suction compartment to which suction is directly applied, spaced support members defining a longitudinal beam secured at its ends only to the suction box structure, a further longitudinal suction compartment formed adjacent the main suction compartment and adapted to receive sucnon only from the main suction compartment by a commumcation between the two compartments, one boundary surface of this further compartment nearer the sealing edges at the mouth of the main compartment being constituted by a wall of the suction box structure itself and the other boundary surface farther from the sealing edges of the main compartment being connected to the longitudinal beam over the length of said beam.

2. A suction-box as in claim 1, wherein the longitudinal beam is disposed inside the suction box body.

3. A beam-like suction box structure for a suction roll of a paper-making machine comprising fixed longitudinal sealing strips along the edges of a main suction compartment of the box structure to contact the roll shell, the box structure being provided with a body portion of hollow generally rectangular section, two flanged beams lying externally alongside the hollow section and secured at the ends of one ilange only of each to the sides of the box structure, the depth of the beams being such that the other flange of each extends beyond the depth of the hollow section, and a further longitudinal suction compartment in communication with the main suction compartment, one boundary surface of this further compartment being constituted by a wall of the hollow section and the other being connected over its length to the extending ilanges of the two beams.

4. A suction-box as in claim 3, wherein the further boundary surface of the further suction compartment is a plate, and a flexible seal round the entire periphery of the plate between its edges and the outer wall of the hollow section complete the further compartment.

5. A suction-box as in claim 3, comprising a tube passing uninterruptedly through the hollow section to provide the communication between the main suction compartment of the box and the further suction compartment.

6. A beam-like suction box structure for a suction roll of a paper-making machine comprising lixed longitudinal sealing strips along the edges of a main suction compartment of the structure to contact the roll shell, the structure being provided with a longitudinal beam secured at its ends only to the suction box structure and with a further longitudinal suction compartment in communication with the main suction compartment, one boundary surface of this further compartment being constituted by a wall of the suction box structure and the other boundary surface farther from the sealing edges of the main compartment being connected to the longitudinal beam over the length of tha-t beam, the box structure being of hollow generally rectangular section, the longitudinal beam being flanged, the ends of one ange thereof being secured to the inner wall of the hollow sec-tion, means defining holes being provided a-t intervals through the outer Wall of the hollow section, connecting members passing through the holes between the other llange of the beam and the farther boundary surface of the further suction compartment, and sealing means closing the holes from that further suction compartment.

7. A suction box as in claim 6, wherein the farther boundary surface of the further suction compartment is a plate, and a exible seal round the entire periphery of the plate between its edges and the outer Wall of the hollow section complete the further compartment.

8. A suction box as in claim 7, wherein the outer wall ofthe hollow section is removable.

9. A suction box as in claim 6, wherein a tube passes uninterrup-tedly through the hollow section to provide the communication between the main suction compartment of the box land the further suction compartment.

10. A suction box as in claim 1, wherein the beam support for the box is external to the box.

ll. A suction box as in claim 10, wherein the beam support is duplicated in the form of two hanged beams lying Ialongside the sides of the box.

References Cited in the tile of this patent UNITED STATES PATENTS 

